The present invention relates to disc drive data storage systems and, more particularly, to fabricating a disc head slider with vertically contoured surface features through a single lithographic mask and etching step.
Disc drives are well known in the industry. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each disc head slider. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.
The slider includes a hydrodynamic (e.g. air) bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider fly above or in close proximity to the disc surface. It is desirable to maintain a substantially constant flying height and provide minimal tribological problems between the bearing surface and the disc surface.
A conventional catamaran slider includes a pair of raised side rails which face the disc surface and form the air bearing surfaces. The raised side rails are separated by an etched cavity and have tapered or stepped leading edges. Additional stepped surfaces have also be formed at various other locations on the slider surface, which are recessed slightly from the bearing surfaces. These surface features are typically formed-with the cavity through a photolithography process. A traditional photolithography process uses binary photo masks with hard edges to create well-defined patterns in a photoresist layer that is applied to the slider surface. The photoresist pattern is then transferred to the slider surface through an etching or ion milling process.
A traditional photolithography process has certain limits on the types of features that can be patterned and lacks flexibility in shaping the transition geometry between different vertical levels on the bearing surface. A traditional photolithography process can produce only two-dimensional features in the horizontal, x-y dimension with each mask and resist pattern. It cannot directly produce a linear or non-linear profile in the vertical, z-dimension on the slider surface. In addition, a traditional photolithography process requires multiple photo/etching process steps in order to produce features having multiple depths. This decreases the throughput of the fabrication process and increases fabrication costs and cycle time. Also, a multiple-step photolithography process has difficulty in achieving tight process tolerance control since error can be introduced with each mask alignment.
There is a thus continuing need for improved fabrication processes of vertically contoured slider surface features which can be used to improve performance of the slider or read/write head.